請問版友們在大嶼山有無見過松鼠？香港有無關於松鼠的研究呢？
唔該曬

文獻記載赤腹松鼠兩個亞種的分佈，可參考：
http://www.afcd.gov.hk/tc_chi/conservation/hkbiodiversity/database/popup_record.asp?id=3769
不過個人仍然未曾領略到如何分辨安徽及泰國亞種

作為引入種，赤腹松鼠的分佈很可能視乎當初放生的地點
故大嶼山無松鼠並不令人意外

我覺得比較奇怪的是赤腹松鼠在新界似乎相當局限於新界中部
理論上 大欖/大帽山/大埔滘 與 九龍群山/馬鞍山/西貢 並無城市帶相隔，松鼠應可散播至後面幾個大區
所以反而想問有無版友曾在新界中部以外見過赤腹松鼠？

唔該Aland，唔知道漁護處引入一些新品種時候有咩野原則呢？

在落馬洲村附近見過, 另外如果你睇返香港陸上哺乳動物圖鑑, 新界西其實有record

新界北 上水 雞嶺都有見過~

以我所知，赤腹松鼠應該並非漁護署引入，pet release 機會較大
如果漁護署引入應該不會刻意分別引進兩種不同亞種.........

關於刻意引入物種，香港其實例子不多，以生態原因引入者更少
只知有研究嘗試用各種菟絲子克制微甘菊，引入食蚊魚控制蚊蟲數量（後者成生態災難）
其他引入、重新引入的物種，絕大部分為佛教放生、意外引入

重新引入/引入物種其實相當具爭議性
我自己原則上同意重新引入部分曾經在香港出現過的keystone species，如鼯鼠（飛鼠）、水鹿等
不過宜謹慎，否則只會重演食蚊魚所造成的生態災難

關於引入/重新引入等生態議題，我強烈推薦《香港生態情報》一書
此書絕對稱得上本地生態天書

身在外地，我本香港陸上哺乳動物圖鑑同我相隔半個地球............

望返論壇記錄，大欖同新界北應該有
但東北（八仙嶺/船灣）、西貢似乎無記錄？未知條分佈界線在何？

另外，雖然文獻寫赤腹松鼠愛好埋藏堅果，但感覺上堅果最多的山地林從來不見其踪影
反而市區/林緣依賴培栽植物花果為生的佔大多數
赤腹松鼠對一堆堅果的傳種作用似乎有限？

我都知道引進新物種要非常非常小心，好似生魚，澳洲引入toad；結果成為生態災難。松鼠應該本身香港有既，重新引進又點樣呢？

其實我系唸緊如果重新引進原有既松鼠，睇睇會不會對殼斗科既植物多個傳播媒界，因為殼斗科植物應該原本系香港4大科之一。

除老虎/鱷魚等對行山人士安全有威脅的物種外
重新引入locally extinct species基本上爭議不大
甚至引入外來物種代替原有megafauna都有成功例子
例如外國有不少外島在Pleistocene megafaunal extinctions裡失去了本地陸龜
近年就有計劃引入其他外來陸龜維持本地植披結構
聽聞相當成功

參考：https://theraptorlab.wordpress.com/2013/08/05/slow-steady-rewilding-with-tortoises/

反觀香港，重新引入松鼠/飛鼠等物種去幫助殼斗科、茶科等樹種傳種是有需要
但問題是究竟香港曾經有過的是甚麼物種？是否仍然存在於鄰近地區？
如果引入後繼續如赤腹松鼠般，不存在於原生密林/次生林
對本地生態其實無大幫助

其實有無人知東亞其他地區殼斗科如何傳種？

[ 本帖最後由 Aland 於 2017-4-27 00:42 編輯 ]

Aland,
  謝謝你既回覆，對了，香港曾經出現什麼品種呢？我睇過一份paper話，香港出現的兩種松鼠都系外來品種。赤腹松鼠只有在香港島出現，大概有一半它們的食物是吃外來品種植物的果，另外有1x-2x 食物來自人類，可能系佢地身處地方太多或者太容易找到食物，他們不需要到原生密林/次生林找食物。假設它們被放到大嶼山可能要找大自然的種子吃，那麼對種子傳播可能有正面作用？


“但問題是究竟香港曾經有過的是甚麼物種？是否仍然存在於鄰近地區？
如果引入後繼續如赤腹松鼠般，不存在於原生密林/次生林”

多謝你initiate個討論就真.........

入正題

I may be overly pedantic
但嚴格而言香港只有一種松鼠——赤腹松鼠
「亞種」和「種」始終有分別
印象中亞種之間應該可以interbreed？（有錯請指正）

赤腹松鼠何以依賴人類/培栽植物為生，有幾個可能性
1. 如你所講，現有棲地無數量可觀、更「天然」的食物來源
2. 本地原生林/次生林（就算大嶼山）完全無合適食物
3. 堆松鼠來自captivity，依賴市區已成習慣
4. 原生果子狸爭食

個人認為1是2/3/4的後果，非成因
始終港島半山/嘉道理與成熟森林直接相連
要入密林棲息，太容易

2其實都未必完全講得通
安徽、泰國氣候/植披雖然與香港不盡相同
但既然松鼠可以學會食洋紫荊、木棉、朱纓花
很難想象原生樹林完全無合適食物

我覺得主因應該是3
培栽植物/人類垃圾營養價值高
一群曾經在鐵籠中生活，放生後依賴林緣/市區食物的松鼠
未必能重新適應自然環境
美國各國家公園不斷提醒遊人不要喂飼松鼠也是出於同一原因

至於4，如果是事實，其實相當值得研究
尤其赤腹松鼠自然分布與果子狸有不少重疊

當然還有一個可能性
就是樹林其實有松鼠，只是數量少我們視而不見而已
有無人手上有本香港哺乳動物圖鑑幫我查camera trap data？

[ 本帖最後由 Aland 於 2017-4-27 12:26 編輯 ]

無人可以確認，但肯定非常非常精彩
至少 短吻鱷、亞洲象、犀牛、葉猴、五間狸、赤狐、華南虎、飛鼠、水鹿、豹 應該全部都曾在香港出現過
基本上無論如何重新引入，香港的megafaunal diversity都與以往相距甚遠

其實此值得深思
既然完全無可能回復到人類大幅干預前的狀態，究竟conservation應該採取甚麼方向？
上面list入面有個別物種對維持生境多樣化 (or beta diversity)非常重要
例如大象，因為夠大力，在不少熱帶國家乃推倒樹木，逆轉演化，維持空曠生境的重要物種
以香港低地林規模，應該再難support大象
如此，阻止溼地演化成密林工作由誰負責？

[ 本帖最後由 Aland 於 2017-4-27 12:29 編輯 ]

好耐冇見到深入嘅討論喇~雖然我唔識植物, 但容許我吹下水~~

有關seed dispersal可以參考返學者Richard Corlettr呢篇文獻:
Seed dispersal in Hong Kong, China: past, present and possible futures
https://www.researchgate.net/pro ... 256ed8782000000.pdf

以上提過嘅動物, 有唔少係確確實實喺香港出現過
但我地已經冇辦法肯肯定咁去知道what have we lost
重新引入呢d物種, 我相信唔會係短期內(5-10年)發生, 因為有太多問題要解決
但長遠對香港次生林生境幾重要

至於第二個問題: 阻止溼地演化成密林工作由誰負責？
正正因為我地唔知道what have we lost, 好多以前發生喺本地嘅ecological process已經"失傳"
勉強要搵嘅, 水牛可以嗎?
但其實除左濕地, 仲有其他生境面臨同一個情況
好似高地嘅grassland/shrubland, 同樣support特別嘅物種(e.g.大草鶯)
但理論上呢類生境係會慢慢success到woodland
咁我地又應該點做呢? 係制止natural succession? 定由得佢?

it is becoming "philosophical" but was a good discussion. even we think in terms of "mega" events like the first arrival of humanoids/human, change from hunter-gatherer to agriculture settlement (let go the industrial revolution which we have better knowledge of the environmental/extinction effects), we could only guess what "human" have done to the "original" megafaunal diversity of every human touched habitats, either temporary or permanent. in a way, human is but one of nature's produce... isnt it?

for times not so long ago as to involve too many natural/climatic/geologic changes (eg earthquake, tsunami, volcanic eruption, glacial activity, sedimentation... to ice age, tectonic movement... etc). the "original" megafauna should also be under continuous changes by "BDIE", competition, adaptive radiation, micro-evolution and speciation, etc.

think of some isolated places where ancient "living fossils" have survived until today. panda and ancient plants around sichuan, mammoth (until recently) of siberia, coelacanth in east africa and indonesia. lungfishes in australia, s. america & africa, it seemed that extinction of many once diversely distributed similar species in mega scale have occurred over the geological ages yet ancient characters could be preserved for so long if given the rare chance.

the key point i think is that human has the ability now to drastically change the earth with previously unseen scale and speed (like by nuclear or chemical or biological war in one extreme). but we see and seek "equilibrium" and "stability" in common sense and knowledge (whether true or false? right or wrong?). we know we have done so much irreversible things in such a short time that are ultimately of no good contribution to our own future and generations then, that we started to think conservation.

note that there are many people with totally different knowledge or ignorance out there!

we have wildlife (megafauna) poacher, trader, cook and taster, crafter and skin/shell/bone/tooth/meat/blood lover of all kinds. are we as conservationist also thought deep enough about the reason for some of these phenomenon?

we have every reason to exterminate disease causing agents (cf conservation in philosophical sense). think of the pox virus, which are now only suviving in special cell cultures in a few labs (human is its natural host that unfortunately it tends to make very ill or kill). we have done a long way to exterminate unsuccessfully one ancient species - the cockroach (have anyone marvelled about the cockroach, as a wildlife!). we are struggling with the same efforts towards many other species. of the many disease causing organisms, some are real beauties under the microscope or in culture medium. we could also learn a lot from the agility of mosquito and common fly!

on the other hand, why are dolphins being so brutally butchered in a small cove in japan? and why do they still keep on hunting whales in view of their relative high level of common education and scientific knowledge? any and what kind of political, cultural, social or criminal factors are behind this dilemma? how should we understand, tolerate, protest or condemn these activities?

why are some people keep on using, as food, tonic or medicine, elephant tusk, rhinocerus horn, seahorse, tiger bone, bear bile juice, pangolin scale, eagle & owl, tutle & lizard,... to things like shark fin, swallow nest?

as a member of the oriental race, perhaps we have some or more special feeling or understanding on these?

on the many introduced species, you have mentioned varied reasons and results, and it seemed a case by case scenario? what should be the standard or should there be any standards? consider the local wildlife and conservation mentality as examplified by our media reports on wild boar sightings and shootings, our exploding population and the desire and need for new land, the need for jobs, for security, for our children, immigrants, visitors and our own daily living... what is the outlook and direction for conservation in hk? on a smaller agenda, what message and action are in need of popularizing and promoting right now?

we have done something as i see in over 30 years as a bystander, although considered so minimal and inadequate maybe. we need to continue to do something, or more.

[ 本帖最後由 jasonpoon 於 2017-4-27 16:30 編輯 ]

其實香港近一兩百年內仍然存在的哺乳類動物，大都在文獻內有記錄
香港有不少megafauna，其實是到二戰前後伐林摧毀>90%本地樹林的時候才在本地絕跡
至少大靈貓（五間狸）、赤狐 等幾個物種肯定曾經在香港出現過
而這類物種，其實附近地區仍然有相當可觀的族群，重新引入絕對可行

但引入這些物種究竟能否解決seed dispersal問題，值得相榷
上面你引用的文章其實都有提到，香港堅果類植物的seed dispersal應該由rodents負責
而rodents的文獻記錄遠較megafauna差
引入未能證實在香港曾經出現過的物種爭議肯定大

現時漁護署對重新引入的態度肯定是傾向謹慎
但終日話要繼續研究，要繼續研究，其實亦非可行之計
The clock is ticking，重新引入有時限，越遲做越多物種受牽連

以植物角度，數一數，原生殼斗科36種
其中3種似乎已經一段時間無出現過（白櫟、鼠刺葉柯、苦櫧）
另外17種分佈狹窄或少見樹苗（麻櫟、木薑葉青岡、油葉柯、櫟葉柯、廣南柯、耳柯、厚斗柯、尖葉柯、雷公青岡、福建青岡、櫟子青岡、檳榔青岡、吊皮錐、毛錐、栲、甜櫧、米櫧）
個人觀察，上述不少物種大有可能在一兩代內消失
其餘16種分佈比較廣而且數量稍多，有機會如某些南美evolutionary ghosts般在物種消失後存在一段長時間
但就算樹苗比較多的物種（例如竹葉青岡），亦似乎只能靠落果發芽繁衍

如果將安息香科、茶科、樟科 等納入統計
情況就更加令人擔憂


米埔印象中有project用水牛維持濕地生態價值
效果如何？

香港的高山草坡生境究竟會否全部經由succession變成密林，其實是一個有趣的議題
我兩派意見都聽過，有一派覺得本地部分地區雨量/風勢可以在一定程度上阻止succession
但無論如何，succession在不少山地生境絕對正在以頗快的速度發生
而如果要在大帽山紅花嶺大幅移除林木保護大草鶯，肯定惹來反彈
甚至幾年前有關當局打毒釘殺死大頭茶保護香港杜鵑，已經引起不少爭議
外國當下流行的一個concept，rewilding，即重新引入，甚至從外來引入相關megafauna, and let them do the work
但香港一來生境規模太小，二來根本未確實知道當初高山草地、濕地究竟是何以維持
要做rewilding，未必可行

I think we have to first accept a cold hard fact——no ecosystem is truly natural now. Even the Amazon rainforest was once packed with human settlements and agricultural land, and that is even before Europeans reached South America. In fact, Europeans killing off 99% of the inhabitants of South America led to such rapid forest growth that the world entered a little ice age due to falling CO2 levels from the newly sequestered carbon. If we view the fauna and flora as species all living on human disturbed habitats, with various degrees of present/past intervention, we will soon come to the conclusion that minimal intervention is not a possible way out for conservation. Locally, species that once lived in wetlands created by meandering rivers, grasslands maintained by elephants, or dense natural woodland, are now adapted to live in human created habitats such as abandoned paddies, fire-maintained grasslands, and abandoned tea plantations respectively. As we could never go back to the original state, some sort of intervention or active management is needed for the continued survival of these species. The problem is, this message is not coming through, even among naturalists, among which many still believe that conservation is, strictly, no intervention.

As for the point about what we define as 'pathogens' and 'pests'. I believe is impractical and too extreme to convince people to love the mosquitoes and cockroaches wandering around the household. However, this does raises the issue of the purpose of conservation. Is it merely to allow continued appreciation of their aesthetic value? Or is it because organisms have the intrinsic right to be living on the planet? Alternatively, as economists might be keen to point out, is conservation aimed at protecting the value of the ecosystem services provided by the ecosystem? I tend to believe that all of the above are relevant and valid reasons for conservation, but when it comes down to political decisions about whether to sacrifice conservation for development, it is often the case that some arguments for conservation are stronger than others. How should we decide what do forgo what we face these struggles? Question for everyone to ponder

越來越有趣，我都覺得系第三個原因比較似，好似猴子一樣，過渡依靠人類食物結果就唔自己找食物，並非不足夠天然食物。
  另外我昨天看過一份報告，大嶼山並不存在松鼠與果子狸。有趣地喬木比較，大嶼山只有新界的1/3喬木品種，所以數據上可能食物來源的確有頗大的限制。
果子狸是否會吃堅果? 香港植物漿果比例應該比堅果多好多，如果堅果比例多D應該就唔會競爭太激烈?

is it likely that omnivorous wild animals will try to find easy food from around human settlements. other eg include the polar bear, wolf (which becomes dog by domestication), boar (becomes pig), pheasant (becomes chicken), etc.

it is interesting that you mention the squirrals did not (or have not yet) crossed the narrow sea barriers to enter lantau. or they could not establish there due to lack of nuts? think of the Paguma that is also absent from lantau but which should be native for a much longer period, the lack of both nutty & fruity trees in lantau maybe the reason but that does not answer why the squirrels, let alone the Paguma, are absent in lantau.

squirrels are indeed a more temperate species group when their global distribution is considered. i think global warming could indeed hinder their range expansion into the subtropics or tropics.